The northern Bay of Bengal is one of the most dynamic parts of the ocean. This area is strongly influenced by river water, heavy rainfall, changing winds, and seasonal shifts in temperature and salt levels. These conditions affect how warm and salty layers of water form and mix, which in turn can influence storms, climate, and marine life.

In this study, we used a numerical model to take a very detailed look at how different environmental factors shape the water layers in this region. We compared a high‑resolution model with a lower‑resolution version and found that the higher‑resolution model was much better at capturing local details. We also identified which factors matter most: river water and wind‑driven ocean currents have the biggest impact on the surface water layers, while temperature, rainfall, and downward‑moving currents strongly affect deeper layers.

Understanding these processes is important because they influence the formation of tropical cyclones and help locate good fishing grounds. The results from this work provide a strong foundation for developing an ocean forecasting system for Bangladesh, which could improve disaster preparedness and support sustainable use of the ocean’s resources.